A Vaccine against Rumen Methanogens Can Alter the Composition of Archaeal Populations

Abstract

The objectives of this study were to formulate a vaccine based upon the different species/strains of methanogens present in sheep intended to be immunized and to determine if a targeted vaccine could be used to decrease the methane output of the sheep. Two 16S rRNA gene libraries were used to survey the methanogenic archaea in sheep prior to vaccination, and methanogens representing five phylotypes were found to account for >52% of the different species/strains of methanogens detected. A vaccine based on a mixture of these five methanogens was then formulated, and 32 sheep were vaccinated on days 0, 28, and 103 with either a control or the anti-methanogen vaccine. Enzyme-linked immunosorbent assay analysis revealed that each vaccination with the anti-methanogen formulation resulted in higher specific immunoglobulin G titers in plasma, saliva, and rumen fluid. Methane output levels corrected for dry-matter intake for the control and treatment groups were not significantly different, and real-time PCR data also indicated that methanogen numbers were not significantly different for the two groups after the second vaccination. However, clone library data indicated that methanogen diversity was significantly greater in sheep receiving the anti-methanogen vaccine and that the vaccine may have altered the composition of the methanogen population. A correlation between 16S rRNA gene sequence relatedness and cross-reactivity for the methanogens (R 2 ‫؍‬ 0.90) also exists, which suggests that a highly specific vaccine can be made to target specific strains of methanogens and that a more broad-spectrum approach is needed for success in the rumen. Our data also suggest that methanogens take longer than 4 weeks to adapt to dietary changes and call into question the validity of experimental results based upon a 2-to 4-week acclimatization period normally observed for bacteria.Livestock are a major source of methane production in Australia, with over half of the total anthropogenic methane emissions attributed to them (1). Methane from livestock is produced as a by-product of enteric fermentation and is vented mostly via the mouth and nose by belching and exhalation, with a small amount expelled via the anus (12). There are many approaches being investigated for reducing the methane production of ruminant livestock (for examples, see references 3 and 22). Our laboratory has been working on a novel immunization approach to decrease the numbers and/or activity of the methanogenic archaea (i.e., methanogens) in the rumen. Wright et al. (30) vaccinated sheep with an anti-methanogen vaccine that was based on three strains (1Y, AK-87, and ZA-10) belonging to the genus Methanobrevibacter and produced a 7.7% decrease in methane production per kg of dry matter (DM) intake (DMI). Wright and his colleagues (28) later discovered that less than 20% of the different species of methanogens detected in those sheep were closely related to the methanogens in the vaccine. On the basis of these findings, it was suggested that greater methane aba...

Examination of the Rumen Bacteria and Methanogenic Archaea of Wild Impalas (Aepyceros melampus melampus) from Pongola, South Africa

“…However, the rumen methanogens present in sheep from Venezuela had 19.2 % of all clones with 99 % similarity to M. thaueri and had 39.4 % (41/104) of clones with 97.9-98.5 % identity to Methanobrevibacter gottschalkii [42]. The absence of M. thaueri-related sequences was observed in alpacas from Vermont, water buffalo on three different diets, sheep in Western Australia, sheep from Queensland, Australia, and in Sika deer from China [26,34,41,43,47]. Comparing the methanogen diversities of previous studies to the present study suggests that both the diet of the impala and the unknown factors in the rumen allow for M. thaueri-like methanogens to thrive over other methanogen species.…”

Progress in the development of vaccines against rumen methanogens

“…A similar vaccine was used in a New Zealand study, but in that trial there was no significant reduction in methane emissions (Leslie et al, 2008). The authors of the initial Australian study subsequently discovered that ,20% of the different species of methanogens detected in the sheep were closely related to the methanogen strains used in the vaccine (Wright et al, 2006;Williams et al, 2009). A further vaccination trial was conducted in sheep using a more targeted vaccine based on the different species of methanogens found to be present in the animals (Williams et al, 2009).…”

Effect of Phenotypic Residual Feed Intake and Dietary Forage Content on the Rumen Microbial Community of Beef Cattle

“…Although the negative association between Entodinium spp. and CH 4 and CH 4 GEI was surprising given that these hydrogen producers are deemed to positively influence CH 4 production, it has also been reported that methanogens take longer than other rumen microbes to adapt to changes in their environment (57). Further-more, methanogenesis could potentially be altered due to fluctuations in the abundances of other H 2 -producing rumen microbes.…”